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United States Department of Agriculture

Agricultural Research Service

Title: Phytosanitary Status of California Citrus

Authors
item Krueger, Robert
item Bash, John - UCR, PLANT PATHOLPGY
item Lee, Richard

Submitted to: International Organization of Citrus Virologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 7, 2004
Publication Date: May 1, 2007
Citation: Krueger, R., Bash, J., Lee, R.F. 2007. Phytosanitary status of california citrus. International Organization of Citrus Virologists Abstracts, Page 102.

Interpretive Summary: The certification/registration program for citrus nursery stock in California is old and well established. However, changing conditions and challenges sometimes necessitate changes in the regulations. Some recent proposed changes to regulations include inclusion of mandatory stubborn testing to complement the current tristeza, psorosis, and exocortis tests. Revision of the existing interior tristeza quarantine regulations for areas not participating in mandatory tree removal program is being considered to protect nurseries in those geographic areas, but as of this writing have not been implemented. Citrus leaf blotch virus (CLBV) has recently been reported to be seed-transmitted, which might lead to compromise of rootstock seed-source trees. However, the apparently close identity of CLBV and Dweet mottle virus have probably protected the industry from wide-spread contamination with CLBV since the biological indexing would have detected CLBV before it was accepted as a 'new' virus. Current Citrus Clonal Protection Program (CCPP) and NCGRCD bud sources are currently being tested for CLBV utilizing a PCR test; any positives found will be re-sanitized. We are also attempting to establish laboratory-based back up tests for all currently utilized biological indexes.

Technical Abstract: The certification/registration program for citrus nursery stock in California is one of the oldest in the world and has served as a model for other programs. Although this program functions efficiently in its present form, new challenges sometimes arise that force modifications or improvements to the program. Some recent proposed changes to regulations include inclusion of mandatory stubborn testing to complement the current tristeza, psorosis, and exocortis tests. To better protect nurseries, revision of the existing interior tristeza quarantine regulations for areas not participating in mandatory tree removal program is being considered. However, as of this writing these proposed changes have not been implemented. Recent reports of seed-transmission of Citrus leaf blotch virus (CLBV) from Spain have prompted a re-examination of existing bud sources in California. The apparently close identity of CLBV and Dweet mottle virus, which was first reported in the 1960s, have probably protected the industry from wide-spread contamination with CLBV since the biological indexing would have detected this virus before it was formally published as a 'new' virus. However, current Citrus Clonal Protection Program (CCPP) and NCGRCD bud sources are currently being tested for CLBV; any positives found will be re-sanitized. We are also attempting to establish laboratory-based back up tests for all currently utilized biological indexes. These and other challenges make the need for eternal vigilance at the NCGRCD and the CCPP, the two programs primarily concerned with the phytosanitary health of the California citrus industry.

Last Modified: 12/18/2014
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